The present invention relates to an imaging apparatus, which is capable of playing back a shot image as an electronic image in real time, and recording the electronic image, and playing back the recorded electronic image, and which is applicable to a digital camera, a mobile phone with a digital camera, a video camera and the like.
In recent years, a shooting technology of an electronic image used for a digital camera and the like has been more widely used along with technical progress, and thereby a shooting is possible under a shooting condition where the shooting is conventionally impossible. As an example, there is a digital camera which is capable of performing a long exposure to shoot a low-brightness photographic subject such as a night sky at high picture quality. However, to shoot a high picture quality image using the long exposure without camera shake, it is necessary to reliably stabilize a digital camera by use of a tripod or the like for a long time in many cases. Accordingly, in a case where a position of the stabilized digital camera is moved during the long exposure for some reason, the shooting may not be satisfactory. Moreover, in this case, a user can not perform a subsequent shooting operation until the long exposure is over, and as a result, the user wastes time. In addition, from the viewpoint of power saving of the digital camera, a power consumption of the digital camera is also a problem.
As one of the technologies to solve such a problem, there is an invention disclosed in Japanese patent application publication number 2005-117395. Japanese patent application publication number 2005-117395 discloses that while performing a long exposure operation in a long exposure mode, a pixel signal is read out from approximately all pixels of an image sensor at a predetermined cycle, and the pixel signal is added each time the pixel signal is read out, and an image formed by the added pixel signal is displayed on a liquid crystal display (hereinafter, it is referred to as LCD), and when an ending of the long exposure operation is instructed by pressing a shutter release button fully again, or when a determination of obtaining a proper exposure amount is made based on a pixel value of the added pixel signal forming the image, a latest added image recorded in a second image recorder is set to be a recorded image.
According to the invention disclosed in Japanese patent application publication number 2005-117395, it is necessary for a user to press the shutter release button of the digital camera at all times of the long exposure. Even if a camera is stabilized by a tripod or the like, camera shake caused by a user's body such as hands and fingers is transmitted to the camera, and therefore it is difficult to achieve a high picture quality shooting in the long exposure without shake.
There is an invention disclosed in Japanese patent number 3399454, as another conventional technology to solve a problem in the long exposure. Japanese patent number 3399454 discloses that a pixel arrangement plane of an image sensor is divided into a field for displaying and a field for recording, and an exposure time of each field is settable to be different. When a shutter operation is performed, an exposure of the field for recording is started and a charge storage is performed in the field for displaying for a predetermined time, and an image formed on the basis of this charge signal is displayed on an LCD or the like as a display image. An exposure of the field for displaying for a predetermined time and a reading out of an image are repeatedly performed, and an obtained image each time is added to a previously displayed image and displayed. As a result, until the exposure of the field for recording is over, an image display is performed in a digital camera.
According to the invention disclosed in Japanese patent number 3399454, since only an image signal obtained in a part of the image sensor is used for displaying, in a case of checking an image displayed on a high-accuracy display device such as an LCD used for a recent digital camera, there is a limit to checking a subtle image blur.
Additionally, as still another conventional technology, there is an image apparatus disclosed in Japanese patent application publication number 2004-077713. This discloses that a camera shake detector which detects a state of the camera shake is provided, and in a case where there is an image blur which is judged based on the detected shake information, a user is informed of the image blur by the imaging apparatus before shooting, and thereby a shooting failure due to camera shake can be reduced.
According to the invention disclosed in Japanese patent application publication number 2004-077713, a possibility of camera shake occurring is informed by the imaging apparatus to a user before shooting, and thereby it is possible for the user to previously take a measure to prevent camera shake. However, even if a shooting condition before shooting is a condition which does not cause an image blur, and there is no warning, when an image blur occurs during exposure, the shooting becomes a failure as a result.